Variable stiffness fuel rail pulse damper having extended dynamic range

Abstract

A fluid pulse damper having increased dynamic range and sensitivity, being especially useful in suppressing pulsations in the fuel supply rail of an internal combustion engine. The damper is a longitudinal gas-filled plastic pillow having walls formed by opposed flexible short sides and opposed flexible long sides, and includes at least one internal self-contact element, and preferably a plurality of such elements. As the short sides flex, the elements make contact internally, shifting the damper into a different compression regime and extending the pressure/response over an increased range of pressures. A feature of some embodiments is that the inner surface within the contact elements is shifted into tension after the elements make contact, thereby stiffening the damper and increasing the damper's resistance to further deformation. The damper is formed of a plastic such as ultra-high molecular weight polyethylenes, high flow polyetherimides, or tubing grade polyphthalamides.

1. A pulse damper for inclusion within a fluid medium for suppressing pulsations therein, comprising walls having first and second flexible sides connecting and separating third and fourth diaphragm sides, said first, second, third, and fourth sides being sealed at first and second ends thereof to form an elongate pillow having a captive-gas chamber therewithin, at least one of said first, second, third and forth sides being constructed of at least one of a varied cross-section shape and a varied cross-section thickness to produce a non-linear response to said pulsations, wherein said third and fourth sides are tapered in wall thickness. 
   
   
     2. A pulse damper in accordance with  claim 1  said walls are formed from materials including an organic polymer. 
   
   
     3. A pulse damper in accordance with  claim 2  wherein said organic polymer is selected from the group consisting of polyimide, polyamide-imide, polyetherimide, polyphenylene sulfide, polysulfone, polyethersulfone, polytetrafluoroethylene, Ethylene Tetrafluoroethylene (ETFE), Per Fluoro Alcoxy (PFA), Fluorinated Ethylene Propylene (FEP), polyetheretherketone, partially or completely aromatic polyamides aliphatic polyamides acetal, ultrahigh molecular weight polyethylene, polypropylene, copolymers of polypropylene/polyethylene, metalocene polymers, pulyurethane, syndiotactic polystyrene, and aliphatic polyketone. 
   
   
     4. A pulse damper in accordance with  claim 1  wherein said first and second sides are non-planar. 
   
   
     5. A pulse damper in accordance with  claim 1  wherein said first and second sides are convex. 
   
   
     6. A pulse damper in accordance with  claim 1  wherein a portion of said third and fourth sides may be urged into tension during said response of said damper. 
   
   
     7. A pulse damper in accordance with  claim 1  further comprising at least one self-contact element extending inwardly from one of said third and fourth diaphragm sides. 
   
   
     8. A pulse damper in accordance with  claim 7  comprising a plurality of said self-contact elements. 
   
   
     9. A pulse damper in accordance with  claim 1  wherein said fluid medium is a hydrocarbon fuel. 
   
   
     10. A pulse damper in accordance with  claim 9  wherein said pulse damper and said fuel are disposed in a fuel rail of an internal combustion engine. 
   
   
     11. A pulse damper for inclusion within a fluid medium for suppressing pulsations therein, comprising first and second flexible sides connecting and separating third and fourth diaphragm sides, and having a captive-air chamber therewithin, to define a two-stage device wherein said first and second sides are damping of low-amplitude pressure variations in said fluid medium and said third and fourth sides are damping of higher-amplitude pressure variations in said fluid medium, wherein said third and fourth sides are tapered in wall thickness. 
   
   
     12. A fuel rail for an internal combustion engine, said fuel rail comprising an internal pulse damper, including
 walls having first and second flexible sides connecting and separating third and fourth diaphragm sides,  
 said first, second, third, and fourth sides being sealed at first and second ends thereof to form an elongate pillow having a captive-gas chamber therewithin,  
 at least one of said first, second, third and forth sides being constructed of at least one of a varied cross-section shape and a varied cross-section thickness to produce a non-linear response to said pulsations, wherein said third and fourth sides are tapered in wall thickness.  
 
   
   
     13. An internal combustion engine comprising a fuel rail having an internal pulse damper, said damper including
 walls having first and second flexible sides connecting and separating third and fourth diaphragm sides,  
 said, first, second, third, and fourth sides being sealed at first and second ends thereof to form an elongate pillow having a captive-gas chamber therewithin,  
 at least one of said first, second, third and forth sides being constructed of at least one of a varied cross-section shape and a varied cross-section thickness to produce a non-linear response to said pulsations, wherein, said third and fourth sides are tapered in wall thickness.